1. Field of the Invention
The invention relates to a hot-water central heating system with a boiler, which surrounds a combustion chamber, a burner situated beneath the combustion chamber and a hot-water conduit system which is situated above the burner and is provided with a cold-water inflow and a hot-water outflow. Normally, the conduit system for the hot water is disposed on the walls of the combustion chamber so that the firing gases are able to rise without impediment and emerge laterally into the exhaust duct no higher than at a blocked zone situated on the top conduit system on the cover side. By restricting the exhaust cross-section with a smoke-gas butterfly flap it is possible to restrict the velocity of the exhaust gases, but heat utilization of the firing gases is poor, especially when the highest heating output is required and the butterfly flap is fully opened, because such firing gases give up their heat predominantly by radiation and only to a small extent by convection.
It is also known from the German Patent Specification 24 48 790 to dispose a plurality of decks or spiral pipe coils in serial configuration in the combustion chamber of a heating boiler so as to fully utilize the central zone above the combustion chamber as a heat transmitting part. The flow resistance offered to the rising firing gases by the pipe decks is relatively low since the pipe coils are superjacent in spiral configuration and do not intersect.
The French patent specification 2411 373 discloses pipes curved in zig-zag configuration for a hot-water conduit system comprising two decks in which parallel, rectilinear pipe sections intersect in decks but an increased flow resistance offered by intersecting pipes does not come into effect in this known boiler because only two pipe decks are present and the flow direction of the firing gases is substantially parallel with the pipe decks.
2. Object of the Invention
It is an object of the invention to increase the efficiency of heat transfer between firing gases and the water to be heated in a hot water central heating system with pipe coils, installed in decks, as the hot water conduit system.
It is another object of the invention, by means of a relatively tall and nesting hot-water conduit system comprising pipes which intercommunicate in decks, to extract a quantity of heat from the firing gases so that the exhaust gases discharging into the chimney are cooled to less than 400 K. (approximately 130.degree. C.).
It is another object of the invention to continuously regulate the fuel supply in a hot-water central heating system in which water is circulated by a circulating pump, by monitoring the hot water temperature and to provide means for momentarily shutting off the supply of fuel in the event of current failure and stoppage of the circulating pump and to avoid vapour formation in the pipe coils and therefore to avoid excess pressure in the totally enclosed water circulating through the entire heating system.
The invention comprises the features disclosed hereinbelow.